/*
 * $Id: PDFObject.java,v 1.3 2007/09/22 12:48:16 gil1 Exp $ $Date: 2007/09/22
 * 12:48:16 $ This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of the License,
 * or (at your option) any later version. This library is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY; without even the
 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
 * the GNU Lesser General Public License for more details. You should have
 * received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place, Suite 330, Boston, MA 02111-1307 USA
 */
package gnu.jpdf;

import java.io.IOException;
import java.io.OutputStream;
import java.io.Serializable;
import java.util.Vector;

/**
 * This is the base class for all Objects that form the PDF document.
 * 
 * @author Peter T Mount, http://www.retep.org.uk/pdf/
 * @author Eric Z. Beard, ericzbeard@hotmail.com
 * @version $Revision: 1.3 $, $Date: 2007/09/22 12:48:16 $
 */
public abstract class PDFObject implements Serializable
{
    
    /*
     * NOTE: The original class is the work of Peter T. Mount, who released it
     * in the uk.org.retep.pdf package. It was modified by Eric Z. Beard as
     * follows: The package name was changed to gnu.pdf. The formatting was
     * changed a little bit. It is still licensed under the LGPL.
     */

    /**
     * This is the object's PDF Type
     */
    private String type;
    
    /**
     * This is the unique serial number for this object.
     */
    protected int objser;
    
    /**
     * This allows any PDF object to refer to the document being constructed.
     */
    protected PDFDocument pdfDocument;
    
    /**
     * This is usually called by extensors to this class, and sets the PDF
     * Object Type
     * 
     * @param type
     *            the PDF Object Type
     */
    public PDFObject(String type)
    {
        this.type = type;
    }
    
    /**
     * Returns the PDF Type of this object
     * 
     * @return The PDF Type of this object
     */
    public String getType()
    {
        return type;
    }
    
    /**
     * Returns the unique serial number of this object.
     * 
     * @return Unique serial number of this object.
     */
    public final int getSerialID()
    {
        return objser;
    }
    
    /**
     * Returns the PDF document this object belongs to.
     * 
     * @return PDF containing this object
     */
    public final PDFDocument getPDFDocument()
    {
        return pdfDocument;
    }
    
    /**
     * <p>
     * Writes the object to the output stream. This method must be overidden.
     * </p>
     * <p>
     * <b>Note:</b> It should not write any other objects, even if they are it's
     * Kids, as they will be written by the calling routine.
     * </p>
     * 
     * @param os
     *            OutputStream to send the object to
     * @exception IOException
     *                on error
     */
    public abstract void write(OutputStream os) throws IOException;
    
    /**
     * The write method should call this before writing anything to the
     * OutputStream. This will send the standard header for each object.
     * <p>
     * Note: There are a few rare cases where this method is not called.
     * 
     * @param os
     *            OutputStream to write to
     * @exception IOException
     *                on error
     */
    public final void writeStart(OutputStream os) throws IOException
    {
        os.write(Integer.toString(objser).getBytes());
        os.write(" 0 obj\n<<\n".getBytes());
        if (type != null)
        {
            os.write("/Type ".getBytes());
            os.write(type.getBytes());
            os.write("\n".getBytes());
        }
    }
    
    /**
     * The write method should call this after writing anything to the
     * OutputStream. This will send the standard footer for each object.
     * <p>
     * Note: There are a few rare cases where this method is not called.
     * 
     * @param os
     *            OutputStream to write to
     * @exception IOException
     *                on error
     */
    public final void writeEnd(OutputStream os) throws IOException
    {
        os.write(">>\nendobj\n".getBytes());
    }
    
    /**
     * Returns the unique serial number in PDF format
     * 
     * @return the serial number in PDF format
     */
    public String toString()
    {
        return "" + objser + " 0 R";
    }
    
    /**
     * This utility method returns a String containing an array definition based
     * on a Vector containing PDFObjects
     * 
     * @param v
     *            Vector containing PDFObjects
     * @return String containing a PDF array
     */
    public static String toArray(Vector<? extends PDFObject> v)
    {
        if (v.size() == 0)
            return "";
        
        StringBuffer b = new StringBuffer();
        String bs = "[";
        for (PDFObject x : v)
        {
            b.append(bs);
            b.append(x.toString());
            bs = " ";
        }
        b.append("]");
        return b.toString();
    }
}
